This disclosure is related to highly crystalline electrically conducting composites, methods of manufacture thereof and to articles comprising the same.
Electrically conducting organic polymers and semiconducting organic polymers are often used in electronic devices that contain displays (e.g., computers, television sets, and the like), as well as in solar cells, and the like. They are employed in these devices in the form of thin film transistors that have flexible and non-flexible substrates. The combination of easy fabrication using methods such as ink-jet printing and roll-to-roll printing, the mechanical flexibility and modest charge mobilities of solution-processable conducting and semiconducting polymers has the potential to transform the electronics industry. One challenge to the application of polymers in digital electronics is the inherent complexity of the electrical properties of polymer films due to the semi-crystalline nature of many conjugated polymers.
Electron mobility within semiconducting conjugated polymers is dependent upon intrachain and interchain charge carrier hopping events. For example, charge carriers can hop between different chains due to the presence of intermolecular overlapping electron densities, such as π-π stacking. Consequently, the charge carrier mobility can depend on various aspects of the thin-film structure, such as the crystallinity, orientation of the crystals, electron cloud overlap in the unit cell, and the connectivity between ordered regions of the polymer.
U.S. Patent Application 2009/0001359 to Worle is directed to enhanced stability with the addition of metallocenes to polythiophene (PT). However, unsubstituted polythiophene is universally accepted as “insoluble and intractable.” The standard polythiophene deposition approach requires an electrochemical process in which thiophene or bithiophene monomers are polymerized oxidatively at the anode. Research towards solution processing with polythiophene has resorted to extreme techniques, such as an AsF3/AsF5 solvent system or high temperature thermal cleaving of a soluble polythiophene derivate, but the resultant films cannot be re-dissolved following deposition.
It is therefore desirable to have electrically conducting polymeric compositions that display high charge mobility and that are easily processable.